A strut-type suspension used for a four-wheeled vehicle generally includes a strut assembly combined with a damper coil spring. The strut assembly has an external cylinder which is integrated with a main shaft and in which a hydraulic shock absorber is incorporated.
Strut-type suspensions are classified based on whether a piston rod of the strut assembly rotates or not when the strut assembly rotates with the damper coil spring in accordance with steering operation. In either case, in order to allow smooth rotation of the strut assembly, instead of a rolling bearing, a synthetic resin-made thrust sliding bearing may be used between an attachment mechanism for attaching the strut assembly to a vehicle body and an upper end portion of the damper coil spring.
Conventionally, there is a known thrust sliding bearing including: a synthetic resin-made first bearing body placed at the lower side in an axial direction of a piston rod used for a strut-type suspension in a four-wheeled vehicle, and having an annular upper surface and an annular engaging outer peripheral surface; a synthetic resin-made second bearing body superposed on the first bearing body so as to be relatively rotatable about an axis of the first bearing body and having an annular lower surface; a thrust sliding bearing piece interposed between the annular upper surface of the first bearing body and the annular lower surface of the second bearing body and having an annular lower surface which is in a slidable contact with the annular upper surface of the first bearing body and an annular upper surface which is in slidable contact with the annular lower surface of the second bearing body; an annular upper cover having an annular engaging inner peripheral surface engaging the annular engaging outer peripheral surface of the first bearing body, the annular upper cover covering the second bearing body from the upper side in the axial direction; and an annular metal plate interposed between an annular upper surface of the second bearing body and a lower surface of the annular upper cover to be attached to the piston rod (for example, Patent Literature 1).